Fixes answer of question 52 and adds missing quotes

Author: josselinbuils

README-de_DE.md

@@ -1570,9 +1570,9 @@ sayHi();
 ```
 
 - A: `"It worked! Hello world!"`
-- B: `"Oh no an error: undefined`
+- B: `"Oh no an error: undefined"`
 - C: `SyntaxError: can only throw Error objects`
-- D: `"Oh no an error: Hello world!`
+- D: `"Oh no an error! Hello world!"`
 
 <details><summary><b>Antwort</b></summary>
 <p>

README.md

@@ -1572,9 +1572,9 @@ sayHi();
 ```
 
 - A: `"It worked! Hello world!"`
-- B: `"Oh no an error: undefined`
+- B: `"Oh no an error: undefined"`
 - C: `SyntaxError: can only throw Error objects`
-- D: `"Oh no an error: Hello world!`
+- D: `"Oh no an error! Hello world!"`
 
 <details><summary><b>Answer</b></summary>
 <p>