Exit the process when the last thread errors and there is no work to do (#235)

In PR #195, a regression was accidentally introduced. When the process
exits due to an error, it would return 0. This fixes that regression by
checking if there is any work left to do. If the last thread was halted
by an error, the process will exit.

Author: ffrostfall

runtime/include/lute/runtime.h

@@ -30,6 +30,7 @@ struct Runtime
     void runContinuously();
 
     bool hasContinuations();
+    bool hasThreads();
 
     void schedule(std::function<void()> f);
 

runtime/src/runtime.cpp

@@ -95,7 +95,12 @@ bool Runtime::runToCompletion()
             error += lua_debugtrace(L);
 
             fprintf(stderr, "%s", error.c_str());
-            continue;
+
+            // If we have no work to do, then exit the process.
+            if (!hasThreads() && !hasContinuations())
+                return false;
+            else
+                continue;
         }
 
         if (next.cont)
@@ -138,6 +143,11 @@ bool Runtime::hasContinuations()
     return !continuations.empty();
 }
 
+bool Runtime::hasThreads()
+{
+    return !runningThreads.empty();
+}
+
 void Runtime::schedule(std::function<void()> f)
 {
     std::unique_lock lock(continuationMutex);