diff --git a/src/Psalm/Context.php b/src/Psalm/Context.php
index 7531fcbd4a8..97c5564b33b 100644
--- a/src/Psalm/Context.php
+++ b/src/Psalm/Context.php
@@ -741,7 +741,7 @@ public function isPhantomClass(string $class_name): bool
         return isset($this->phantom_classes[strtolower($class_name)]);
     }
 
-    public function hasVariable(?string $var_name): bool
+    public function hasVariable(string $var_name): bool
     {
         if (!$var_name) {
             return false;
diff --git a/src/Psalm/Internal/Analyzer/Statements/Block/IfConditionalAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Block/IfConditionalAnalyzer.php
index 8834b73a5f8..8a9ec5c5846 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Block/IfConditionalAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Block/IfConditionalAnalyzer.php
@@ -34,7 +34,7 @@ public static function analyze(
         Context $outer_context,
         Codebase $codebase,
         IfScope $if_scope,
-        ?int $branch_point
+        int $branch_point
     ): IfConditionalScope {
         $entry_clauses = [];
 
diff --git a/src/Psalm/Internal/Analyzer/Statements/Block/IfElse/ElseIfAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Block/IfElse/ElseIfAnalyzer.php
index 55e99db67ca..de9a0169021 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Block/IfElse/ElseIfAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Block/IfElse/ElseIfAnalyzer.php
@@ -44,7 +44,7 @@ public static function analyze(
         Context $else_context,
         Context $outer_context,
         Codebase $codebase,
-        ?int $branch_point
+        int $branch_point
     ): ?bool {
         $pre_conditional_context = clone $else_context;
 
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
index 1261f421007..5cfba7e5ea4 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php
@@ -908,7 +908,7 @@ public static function checkArgumentsMatch(
     private static function handlePossiblyMatchingByRefParam(
         StatementsAnalyzer $statements_analyzer,
         Codebase $codebase,
-        ?string $method_id,
+        string $method_id,
         ?string $cased_method_id,
         ?FunctionLikeParameter $last_param,
         array $function_params,
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/AtomicMethodCallAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/AtomicMethodCallAnalyzer.php
index 999c0e2e026..ac0f5d241e2 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/AtomicMethodCallAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/AtomicMethodCallAnalyzer.php
@@ -443,7 +443,6 @@ public static function analyze(
             $result,
             $return_type_candidate,
             $all_intersection_return_type,
-            $method_name_lc,
             $codebase
         );
     }
@@ -518,28 +517,19 @@ private static function getIntersectionReturnType(
 
     private static function updateResultReturnType(
         AtomicMethodCallAnalysisResult $result,
-        ?Type\Union $return_type_candidate,
+        Type\Union $return_type_candidate,
         ?Type\Union $all_intersection_return_type,
-        string $method_name,
         Codebase $codebase
     ) : void {
-        if ($return_type_candidate) {
-            if ($all_intersection_return_type) {
-                $return_type_candidate = Type::intersectUnionTypes(
-                    $all_intersection_return_type,
-                    $return_type_candidate,
-                    $codebase
-                ) ?: Type::getMixed();
-            }
-
-            $result->return_type = Type::combineUnionTypes($return_type_candidate, $result->return_type);
-        } elseif ($all_intersection_return_type) {
-            $result->return_type = Type::combineUnionTypes($all_intersection_return_type, $result->return_type);
-        } elseif ($method_name === '__tostring') {
-            $result->return_type = Type::getString();
-        } else {
-            $result->return_type = Type::getMixed();
+        if ($all_intersection_return_type) {
+            $return_type_candidate = Type::intersectUnionTypes(
+                $all_intersection_return_type,
+                $return_type_candidate,
+                $codebase
+            ) ?: Type::getMixed();
         }
+
+        $result->return_type = Type::combineUnionTypes($return_type_candidate, $result->return_type);
     }
 
     private static function handleInvalidClass(
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
index 2ff025c092d..d0005b161c8 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
@@ -20,7 +20,7 @@ public static function analyze(
         Codebase $codebase,
         PhpParser\Node\Expr\MethodCall $stmt,
         ?string $lhs_var_id,
-        ?string $cased_method_id,
+        string $cased_method_id,
         MethodIdentifier $method_id,
         \Psalm\Storage\MethodStorage $method_storage,
         \Psalm\Storage\ClassLikeStorage $class_storage,
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NamedFunctionCallHandler.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NamedFunctionCallHandler.php
index 12c55403a1a..af3fd3be909 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NamedFunctionCallHandler.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/NamedFunctionCallHandler.php
@@ -439,7 +439,7 @@ private static function handleDependentTypeFunction(
         StatementsAnalyzer $statements_analyzer,
         PhpParser\Node\Expr\FuncCall $stmt,
         PhpParser\Node\Expr\FuncCall $real_stmt,
-        ?string $function_id,
+        string $function_id,
         Context $context
     ) : void {
         $first_arg = isset($stmt->args[0]) ? $stmt->args[0] : null;
diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ConstFetchAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ConstFetchAnalyzer.php
index e6264d77bd4..3fd4a4ab2df 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ConstFetchAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ConstFetchAnalyzer.php
@@ -100,7 +100,7 @@ public static function analyze(
 
     public static function getGlobalConstType(
         Codebase $codebase,
-        ?string $fq_const_name,
+        string $fq_const_name,
         string $const_name
     ): ?Type\Union {
         if ($const_name === 'STDERR'
diff --git a/src/Psalm/Internal/Provider/ClassLikeStorageCacheProvider.php b/src/Psalm/Internal/Provider/ClassLikeStorageCacheProvider.php
index 3ad11746392..178f359fcc9 100644
--- a/src/Psalm/Internal/Provider/ClassLikeStorageCacheProvider.php
+++ b/src/Psalm/Internal/Provider/ClassLikeStorageCacheProvider.php
@@ -68,7 +68,7 @@ public function __construct(Config $config)
         $this->modified_timestamps .= $this->config->computeHash();
     }
 
-    public function writeToCache(ClassLikeStorage $storage, ?string $file_path, ?string $file_contents): void
+    public function writeToCache(ClassLikeStorage $storage, string $file_path, string $file_contents): void
     {
         $fq_classlike_name_lc = strtolower($storage->name);
 
diff --git a/src/Psalm/Internal/Provider/ClassLikeStorageProvider.php b/src/Psalm/Internal/Provider/ClassLikeStorageProvider.php
index 41ec69f733f..d1c2c4a700e 100644
--- a/src/Psalm/Internal/Provider/ClassLikeStorageProvider.php
+++ b/src/Psalm/Internal/Provider/ClassLikeStorageProvider.php
@@ -53,7 +53,7 @@ public function has(string $fq_classlike_name): bool
         return isset(self::$storage[$fq_classlike_name_lc]);
     }
 
-    public function exhume(string $fq_classlike_name, ?string $file_path, ?string $file_contents): ClassLikeStorage
+    public function exhume(string $fq_classlike_name, string $file_path, string $file_contents): ClassLikeStorage
     {
         $fq_classlike_name_lc = strtolower($fq_classlike_name);