Added checks to make sure the specified track exists

Added precondition checks to validate input files and paths to return more informative error messages as per #2

node_modules/bs-logger/dist/logger/context.d.ts

@@ -0,0 +1,16 @@
+declare enum LogContexts {
+    application = "application",
+    hostname = "hostname",
+    logLevel = "logLevel",
+    namespace = "namespace",
+    package = "package"
+}
+interface LogContext {
+    [key: string]: any;
+    [LogContexts.application]?: string;
+    [LogContexts.hostname]?: string;
+    [LogContexts.logLevel]?: number;
+    [LogContexts.namespace]?: string;
+    [LogContexts.package]?: string;
+}
+export { LogContext, LogContexts };