undefined assertions in for..in loop

Author: William Duncan

gen/util.ts

@@ -85,11 +85,11 @@ function addExtraReturnsToOperation(operation: Schema.Operation): Schema.Operati
  */
 export function replaceModelTypes(schema: Schema, config: Config): Schema {
     for (const modelID in schema.models) {
-        const model = schema.models[modelID];
+        const model = schema.models[modelID]!;
         for (const fieldID in model.fields) {
-            const field = model.fields[fieldID];
+            const field = model.fields[fieldID]!;
             if (schema.models.find(m => m.name === field.type))
-                schema.models[modelID].fields[fieldID].type = `${config.name}.${field.type}`;
+                schema.models[modelID]!.fields[fieldID]!.type = `${config.name}.${field.type}`;
         }
     }
     return schema;