Throw an error if a text string isn't defined with description of string

src/core/utils/text.tsx

@@ -108,8 +108,14 @@ export const useText = (): UseTextFunction => {
   const { data } = useSelector((state: RootState) => state.text);
 
   return (key: string, { placeholders, count } = { count: 0 }) => {
+    if (!data) {
+      throw new Error(`The translation store is broken.`);
+    }
+    if (!data[key]) {
+      throw new Error(`The translation for ${key} is not defined.`);
+    }
     const textDefinition = constructTextDefinitionFromRawTextTextEntry(
-      data?.[key] ?? key
+      data[key]
     );
 
     const textPlaceholders = { ...(placeholders ?? {}) };

src/tests/unit/text.test.tsx

@@ -76,3 +76,15 @@ test("Should handle plural text definitions", () => {
     );
   });
 });
+
+test("Should throw an error if the text definition is not found", () => {
+  const { result } = renderHook(() => useText(), { wrapper: Wrapper });
+  // We name it t, because that is how we normally use it in the code.
+  const t = result.current;
+
+  act(() => {
+    expect(() => t("nonExistingText")).toThrowError(
+      "The translation for nonExistingText is not defined."
+    );
+  });
+});