Fixes when the search term is null

Author: monika.kwiatek

be/src/Unic.UrlMapper2/code/Services/RedirectSearcher.cs

@@ -63,6 +63,7 @@ protected virtual Redirect MapToSearchResult(RedirectSearchResultItem redirectSe
                 this.logger.Error($"Failed to parse source protocol {redirectSearchResultItem.SourceProtocol}", this);
             }
 
+            var sourceTerm = redirectSearchResultItem.SourceTerm;
             var redirect = new Redirect
             {
                 RedirectSearchData = redirectSearchData,
@@ -71,23 +72,22 @@ protected virtual Redirect MapToSearchResult(RedirectSearchResultItem redirectSe
                 SourceProtocol = sourceProtocol,
                 RegexEnabled = redirectSearchResultItem.RegexEnabled,
                 PreserveQueryString = redirectSearchResultItem.PreserveQueryString,
-                Term = redirectSearchResultItem.SourceTerm
+                Term = sourceTerm
             };
 
-            this.HandlePreserveQueryString(redirect, redirectSearchResultItem);
+            this.HandlePreserveQueryString(redirect, sourceTerm);
             return redirect;
         }
 
-        protected virtual void HandlePreserveQueryString(Redirect redirect, RedirectSearchResultItem redirectSearchResultItem)
+        protected virtual void HandlePreserveQueryString(Redirect redirect, string sourceTerm)
         {
             if (!redirect.PreserveQueryString) return;
 
             redirect.RegexEnabled = true;
-            var sourceTerm = redirectSearchResultItem.SourceTerm;
             if (!string.IsNullOrWhiteSpace(sourceTerm) 
                 && !sourceTerm.EndsWith(Constants.RegularExpressions.QueryStringExpression))
             {
-                redirect.Term = redirectSearchResultItem.SourceTerm + Constants.RegularExpressions.QueryStringExpression;
+                redirect.Term = sourceTerm + Constants.RegularExpressions.QueryStringExpression;
             }
         }
 

be/src/Unic.UrlMapper2/code/Services/RedirectionService.cs

@@ -102,8 +102,8 @@ protected virtual Redirect GetRegexMatch(RedirectSearchData redirectSearchData,
             if (string.IsNullOrWhiteSpace(sourceTerm)) return default;
 
             // We are going to take the one regex redirect which has the longest match within the term
-            var regexMatches = enumerableRedirects.Where(r => r.RegexEnabled && Regex.IsMatch(input: sourceTerm, pattern: r.Term));
-            var regexMatch = regexMatches.OrderByDescending(r => r.Term.Length).FirstOrDefault();
+            var regexMatches = enumerableRedirects.Where(r => r.RegexEnabled && !string.IsNullOrWhiteSpace(r.Term) && Regex.IsMatch(input: sourceTerm, pattern: r.Term));
+            var regexMatch = regexMatches.OrderByDescending(r => r.Term?.Length).FirstOrDefault();
 
             return regexMatch;
         }