Added check for empty artifact list (#24)

* Added check for empty artifact list

buildspec.go

@@ -55,6 +55,10 @@ func (spec buildSpecification) artifactPaths(outputPathPatterns []string, isDir
 }
 
 func (spec buildSpecification) exportIOSApp(artifacts []string, deployDir string) error {
+	if len(artifacts) < 1 {
+		return fmt.Errorf("- No artifacts found")
+	}
+
 	artifact := artifacts[len(artifacts)-1]
 	fileName := filepath.Base(artifact)
 

main.go

@@ -207,10 +207,16 @@ build:
 		} else {
 			artifacts, err = spec.artifactPaths(spec.outputPathPatterns, true)
 		}
+
 		if err != nil {
 			failf("failed to find artifacts, error: %s", err)
 		}
 
+		if len(artifacts) < 1 {
+			failf(`Artifact path pattern (%s) did not match any artifacts on the path (%s).
+Check that 'iOS/Android Output Pattern' and 'Project Location' is correct.`, spec.outputPathPatterns, spec.projectLocation)
+		}
+
 		if err := spec.exportArtifacts(artifacts); err != nil {
 			failf("Failed to export %s artifacts, error: %s", spec.displayName, err)
 		}