Merge pull request #100 from thevpc/fix/exec-command-throws-null-exce…

…ption

Fix `nuts exec` throwing NullPointerException

core/nuts-runtime/src/main/java/net/thevpc/nuts/runtime/standalone/wscommands/exec/DefaultNutsExecCommand.java

@@ -69,10 +69,10 @@ public NutsExecutableInformation which() {
         }
         terminal.out().flush();
         terminal.err().flush();
-        String[] ts = command.toArray(new String[0]);
-        if (ts.length == 0) {
+        if (command == null || command.size() == 0) {
             throw new NutsIllegalArgumentException(traceSession, NutsMessage.plain("missing command"));
         }
+        String[] ts = command.toArray(new String[0]);
         NutsExecutableInformationExt exec = null;
         execSession.setTerminal(terminal);
         NutsExecutionType executionType = this.getExecutionType();