Fix find newline looping to have additional break early cases (#4614)

soh/soh/Enhancements/custom-message/CustomMessageManager.cpp

@@ -376,10 +376,15 @@ static size_t NextLineLength(const std::string* textStr, const size_t lastNewlin
   }
 }
 
-
 size_t CustomMessage::FindNEWLINE(std::string& str, size_t lastNewline) const {
     size_t newLine = str.find(NEWLINE()[0], lastNewline);
     bool done;
+
+    // Bail out early
+    if (newLine == std::string::npos) {
+        return newLine;
+    }
+
     do {
         done = true;
         if (newLine != 0) {
@@ -420,12 +425,13 @@ size_t CustomMessage::FindNEWLINE(std::string& str, size_t lastNewline) const {
         }
         if (!done) {
             newLine = str.find(NEWLINE()[0], newLine + 1);
-            if (newLine != std::string::npos){
+            if (newLine == std::string::npos) {
                 // if we reach the end of the string, quit now to save a loop
                 done = true;
             }
         }
     } while (!done);
+
     return newLine;
 }