refactor: improve

kswift-gradle-plugin/src/main/kotlin/dev/icerock/moko/kswift/plugin/feature/SealedToSwiftEnumFeature.kt

@@ -13,6 +13,7 @@ import io.outfoxx.swiftpoet.CodeBlock
 import io.outfoxx.swiftpoet.EnumerationCaseSpec
 import io.outfoxx.swiftpoet.FunctionSpec
 import io.outfoxx.swiftpoet.Modifier
+import io.outfoxx.swiftpoet.ParameterizedTypeName
 import io.outfoxx.swiftpoet.PropertySpec
 import io.outfoxx.swiftpoet.TypeName
 import io.outfoxx.swiftpoet.TypeSpec
@@ -211,24 +212,44 @@ class SealedToSwiftEnumFeature(
         returnType: TypeName
     ) {
         val paramType: TypeName? = enumCase.param
-        val cast = "as?"
+        val cast: String
         val returnedName: String
 
         if (paramType == null) {
             returnedName = "${enumCase.caseArg}()"
+            cast = if (returnType is ParameterizedTypeName) {
+                // The return type is generic and there is no parameter, so it can
+                // be assumed that the case is NOT generic. Thus the case needs to
+                // be force-cast.
+                "as!"
+            } else {
+                // The return type is NOT generic and there is no parameter, so a
+                // regular cast can be used.
+                "as"
+            }
         } else {
+            // There is a parameter
             returnedName = "obj"
+            cast = if (paramType is ParameterizedTypeName && returnType is ParameterizedTypeName) {
+                if (paramType.typeArguments == returnType.typeArguments) {
+                    // The parameter and return type have the same generic pattern. This
+                    // is true if both are NOT generic OR if both are generic. Thus a
+                    // regular cast can be used.
+                    "as"
+                } else {
+                    "as!"
+                }
+            } else if (paramType !is ParameterizedTypeName && returnType !is ParameterizedTypeName) {
+                // If the parameter and return type is not ParameterizedTypeName
+                // regular cast can be used.
+                "as"
+            } else {
+                // If the parameter and return type have differing generic patterns
+                // then a force-cast is needed.
+                "as!"
+            }
         }
-
-        add("if let sealedInstance = $returnedName $cast $returnType {\n")
-        indent()
-        add("return sealedInstance\n")
-        unindent()
-        add("} else {\n")
-        indent()
-        add("fatalError(\"Type mismatch in sealed property\")\n")
-        unindent()
-        add("}\n")
+        add("return $returnedName $cast $returnType\n")
     }
 
     data class EnumCase(