added checks to mitigate floating point crashes

src/providers/twitch/IrcMessageHandler.cpp

@@ -53,7 +53,10 @@ static float relativeSimilarity(const QString &str1, const QString &str2)
         }
     }
 
-    return z == 0 ? 0.f : float(z) / std::max(str1.size(), str2.size());
+    // ensure that no div by 0
+    return z == 0 ? 0.f
+                  : float(z) /
+                        std::max<int>(1, std::max(str1.size(), str2.size()));
 };
 
 float IrcMessageHandler::similarity(

src/providers/twitch/TwitchMessageBuilder.cpp

@@ -60,6 +60,7 @@ QColor getRandomColor(const QVariant &userId)
         colorSeed = std::rand();
     }
 
+    assert(twitchUsernameColors.size() != 0);
     const auto colorIndex = colorSeed % twitchUsernameColors.size();
     return twitchUsernameColors[colorIndex];
 }