fixed bug where symbolKind was always undefined

lib/src/kind_generator.dart

@@ -1,27 +1,46 @@
 import 'package:analyzer/dart/element/element.dart';
 import 'package:scip_dart/src/gen/scip.pbenum.dart';
 
-SymbolInformation_Kind symbolKindFor(Element element) {
+SymbolInformation_Kind symbolKindFor(Element el) {
   // These mappings are declared in the same order as their symbol parsing
   // counterpart is declared within SymbolGenerator._getDescriptor. Ensure
   // this order stays consistent to ensure the correct kinds are included.
-  final mappings = {
-    ClassElement: SymbolInformation_Kind.Class,
-    // MixinElement: SymbolInformation_Kind.Mixin, // Pending: https://github.com/sourcegraph/scip/pull/277
-    EnumElement: SymbolInformation_Kind.Enum,
-    TypeAliasElement: SymbolInformation_Kind.TypeAlias,
-    // ExtensionDeclaration: SymbolInformation_Kind.Extension, // Pending: https://github.com/sourcegraph/scip/pull/277
-    ConstructorElement: SymbolInformation_Kind.Constructor,
-    MethodElement: SymbolInformation_Kind.Method,
-    FunctionElement: SymbolInformation_Kind.Function,
-    TopLevelVariableElement: SymbolInformation_Kind.Variable,
-    PrefixElement: SymbolInformation_Kind.Namespace,
-    TypeParameterElement: SymbolInformation_Kind.TypeParameter,
-    ParameterElement: SymbolInformation_Kind.Parameter,
-    PropertyAccessorElement: SymbolInformation_Kind.Property,
-    FieldElement: SymbolInformation_Kind.Field,
-  };
+  //
+  // Note, we cannot declare this dynamically via a lookup map since the actual
+  // type of [el], is the Impl counterpart (`ClassElementImpl`). runtimeType
+  // type checking _does not_ take inheritance into account and `is` cannot
+  // be used with variables. Hence the large list of if statements.
+  if (el is ClassElement) {
+    return SymbolInformation_Kind.Class;
+  } else if (el is MixinElement) {
+    // Pending: https://github.com/sourcegraph/scip/pull/277
+    // return SymbolInformation_Kind.Mixin;
+  } else if (el is EnumElement) {
+    return SymbolInformation_Kind.Enum;
+  } else if (el is TypeAliasElement) {
+    return SymbolInformation_Kind.TypeAlias;
+  } else if (el is ExtensionElement) {
+    // Pending: https://github.com/sourcegraph/scip/pull/277
+    // return SymbolInformation_Kind.Extension;
+  } else if (el is ConstructorElement) {
+    return SymbolInformation_Kind.Constructor;
+  } else if (el is MethodElement) {
+    return SymbolInformation_Kind.Method;
+  } else if (el is FunctionElement) {
+    return SymbolInformation_Kind.Function;
+  } else if (el is TopLevelVariableElement) {
+    return SymbolInformation_Kind.Variable;
+  } else if (el is PrefixElement) {
+    return SymbolInformation_Kind.Namespace;
+  } else if (el is TypeParameterElement) {
+    return SymbolInformation_Kind.TypeParameter;
+  } else if (el is ParameterElement) {
+    return SymbolInformation_Kind.Parameter;
+  } else if (el is PropertyAccessorElement) {
+    return SymbolInformation_Kind.Property;
+  } else if (el is FieldElement) {
+    return SymbolInformation_Kind.Field;
+  }
 
-  return mappings[element.runtimeType] ??
-      SymbolInformation_Kind.UnspecifiedKind;
+  return SymbolInformation_Kind.UnspecifiedKind;
 }