Fix error showing protoc logs

Author: raboof

gradle-plugin/src/main/groovy/akka/grpc/gradle/AkkaGrpcPlugin.groovy

@@ -162,14 +162,17 @@ class AkkaGrpcPlugin implements Plugin<Project> {
 
         project.task("printProtocLogs") {
             doLast {
-                Files.lines(logFile).forEach { line ->
-                    if (line.startsWith("[info]")) logger.info(line.substring(7))
-                    else if (line.startsWith("[debug]")) logger.debug(line.substring(7))
-                    else if (line.startsWith("[warn]")) logger.warn(line.substring(6))
-                    else if (line.startsWith("[error]")) logger.error(line.substring(7))
+                if (Files.exists(logFile)) {
+                    Files.lines(logFile).forEach { line ->
+                        if (line.startsWith("[info]")) logger.info(line.substring(7))
+                        else if (line.startsWith("[debug]")) logger.debug(line.substring(7))
+                        else if (line.startsWith("[warn]")) logger.warn(line.substring(6))
+                        else if (line.startsWith("[error]")) logger.error(line.substring(7))
+                    }
                 }
             }
         }
+        project.getTasks().getByName("printProtocLogs").dependsOn("generateProto")
         project.getTasks().getByName("compileJava").dependsOn("printProtocLogs") //TODO logs for multi project builds
 
     }