Check unused @throws annotations on functions (#55)

Cherry-picked from #54

Author: pepakriz

src/Rules/ThrowsPhpDocRule.php

@@ -370,13 +370,13 @@ private function processFunctionEnd(Scope $scope): array
 		$usedThrowsAnnotations = $this->throwsScope->exitFromThrowsAnnotationBlock();
 		$usedThrowsAnnotations = $this->checkedExceptionService->filterCheckedExceptions($usedThrowsAnnotations);
 
-		$classReflection = $scope->getClassReflection();
 		$methodReflection = $scope->getFunction();
-		if ($classReflection === null || $methodReflection === null) {
+		if ($methodReflection === null) {
 			return [];
 		}
 
-		if ($classReflection->isInterface() || $classReflection->isAbstract()) {
+		$classReflection = $scope->getClassReflection();
+		if ($classReflection !== null && ($classReflection->isInterface() || $classReflection->isAbstract())) {
 			return [];
 		}
 

tests/src/Rules/data/unused-throws.php

@@ -8,6 +8,13 @@
 class FooException extends RuntimeException {}
 class BarException extends RuntimeException {}
 
+/**
+ * @throws RuntimeException
+ */
+function foo() { // error: Unused @throws RuntimeException annotation
+
+}
+
 class UnusedThrows
 {