diff --git a/ets2panda/ast_verifier/ASTVerifier.h b/ets2panda/ast_verifier/ASTVerifier.h
index 82c05434b9eb9123e957f3f1e471eef55cc4fa3b..edd854d180e676902b83c79a880c711717515d54 100644
--- a/ets2panda/ast_verifier/ASTVerifier.h
+++ b/ets2panda/ast_verifier/ASTVerifier.h
@@ -91,20 +91,30 @@ public:
         for (size_t i = 0; i < VerifierInvariants::COUNT; i++) {
             enabled_[i] = TreatAsWarning(VerifierInvariants {i}) || TreatAsError(VerifierInvariants {i});
         }
-        if (Options().IsAstVerifierBeforePhases()) {
-            Verify("before");
-        }
     }
 
     ~ASTVerifier()
     {
-        if (!suppressed_) {
-            if (Options().IsAstVerifierAfterPhases()) {
-                Verify("after");
-            }
-            if (HasErrors() || HasWarnings()) {
-                DumpMessages();
-            }
+        ES2PANDA_ASSERT(!HasErrors());
+        ES2PANDA_ASSERT(!HasWarnings());
+    }
+
+    void After()
+    {
+        if (Options().IsAstVerifierAfterPhases()) {
+            Verify("after");
+        }
+        if (!suppressed_ && (HasErrors() || HasWarnings())) {
+            DumpMessages();
+            hasErrors_ = false;
+            hasWarnings_ = false;
+        }
+    }
+
+    void Before()
+    {
+        if (Options().IsAstVerifierBeforePhases()) {
+            Verify("before");
         }
     }
 
diff --git a/ets2panda/checker/types/ets/etsFunctionType.cpp b/ets2panda/checker/types/ets/etsFunctionType.cpp
index 133c53eee87cf54b4f8942c4cc2f37457b5baf8b..0e0be3910bc733ea5487d94f6be5716aaadcb3df 100644
--- a/ets2panda/checker/types/ets/etsFunctionType.cpp
+++ b/ets2panda/checker/types/ets/etsFunctionType.cpp
@@ -85,6 +85,7 @@ static ETSObjectType *FunctionTypeToFunctionalInterfaceType(ETSChecker *checker,
 
         auto substitution = Substitution {};
         ES2PANDA_ASSERT(functionN != nullptr);
+        ES2PANDA_ASSERT(nPosParams <= functionN->TypeArguments().size());
         for (size_t i = 0; i < nPosParams; i++) {
             substitution.emplace(functionN->TypeArguments()[i]->AsETSTypeParameter(),
                                  checker->MaybeBoxType(signature->Params()[i]->TsType()));
diff --git a/ets2panda/compiler/core/compilerImpl.cpp b/ets2panda/compiler/core/compilerImpl.cpp
index cd36b35536ca68b350e211dba1cc2ac976942337..539573f68cef867f68908e67f72726a508a3e1dd 100644
--- a/ets2panda/compiler/core/compilerImpl.cpp
+++ b/ets2panda/compiler/core/compilerImpl.cpp
@@ -148,6 +148,7 @@ static bool RunVerifierAndPhases(public_lib::Context &context, parser::Program &
     const auto verifierEachPhase = options.IsAstVerifierEachPhase();
 
     ast_verifier::ASTVerifier verifier(context, program);
+    verifier.Before();
 
     bool afterCheckerPhase = false;
     while (auto phase = context.phaseManager->NextPhase()) {
@@ -177,6 +178,7 @@ static bool RunVerifierAndPhases(public_lib::Context &context, parser::Program &
         }
     }
 
+    verifier.After();
     return true;
 }
 
diff --git a/ets2panda/ir/ts/tsArrayType.cpp b/ets2panda/ir/ts/tsArrayType.cpp
index 93a56fa2084f5ec91d28187c9bf354526845e15e..9d066ff5d72177b74f969766908e64c39f2ceefa 100644
--- a/ets2panda/ir/ts/tsArrayType.cpp
+++ b/ets2panda/ir/ts/tsArrayType.cpp
@@ -118,6 +118,7 @@ TSArrayType *TSArrayType::Clone(ArenaAllocator *const allocator, AstNode *const
         AnnotationUsage *clonedAnnotationUsage;
         for (auto *annotationUsage : Annotations()) {
             clonedAnnotationUsage = annotationUsage->Clone(allocator, clone);
+            ES2PANDA_ASSERT(clonedAnnotationUsage != nullptr);
             annotationUsages.push_back(clonedAnnotationUsage->AsAnnotationUsage());
         }
         clone->SetAnnotations(std::move(annotationUsages));