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/index.d.ts

@@ -0,0 +1,8 @@
+import { LogMethod, Logger, createLogger, lastSequenceNumber, resetSequence } from './logger';
+import { LogContext, LogContexts } from './logger/context';
+import { LogLevelName, LogLevels, logLevelNameFor, parseLogLevel } from './logger/level';
+import { LogMessage, LogMessageFormatter, LogMessageTranslator, registerLogFormatter, resetLogFormatters } from './logger/message';
+import { rootLogger, setup } from './logger/root';
+import { DEFAULT_LOG_TARGET, LogTarget, parseLogTargets } from './logger/target';
+import * as testing from './testing';
+export { rootLogger as default, rootLogger as logger, setup, createLogger, DEFAULT_LOG_TARGET, lastSequenceNumber, LogContext, LogContexts, Logger, LogLevelName, logLevelNameFor, LogLevels, LogMessage, LogMessageFormatter, LogMessageTranslator, LogMethod, LogTarget, parseLogLevel, parseLogTargets, registerLogFormatter, resetLogFormatters, resetSequence, testing, };