Don't return complex words if premium data is not available

packages/yoastseo/src/languageProcessing/languages/de/helpers/checkIfWordIsComplex.js

@@ -17,7 +17,7 @@ export default function checkIfWordIsComplex( config, word, premiumData ) {
 	// All words are converted to lower case before processing to avoid excluding complex words that start with a capital letter.
 	word = word.toLowerCase();
 
-	// The German word is not complex if its length is 10 characters or less.
+	// The German word is not complex if its length is 10 characters or fewer.
 	if ( word.length <= lengthLimit ) {
 		return false;
 	}

packages/yoastseo/src/languageProcessing/researches/wordComplexity.js

@@ -38,18 +38,22 @@ const getComplexWords = function( currentSentence, researcher ) {
 	// Filters out function words because function words are not complex.
 	// Words are converted to lowercase before processing to avoid excluding function words that start with a capital letter.
 	const words = allWords.filter( word => ! ( checkIfWordIsFunction ? checkIfWordIsFunction( word ) : functionWords.includes( word ) ) );
-	const results = [];
+	const result = {
+		complexWords: [],
+		sentence: currentSentence,
+	};
+
+	if ( ! premiumData ) {
+		return result;
+	}
 
 	words.forEach( word => {
 		if ( checkIfWordIsComplex( wordComplexityConfig, word, premiumData ) ) {
-			results.push( word );
+			result.complexWords.push( word );
 		}
 	} );
 
-	return {
-		complexWords: results,
-		sentence: currentSentence,
-	};
+	return result;
 };
 
 /**