imeta aborts with an uncaught exception on commands when the file is not provided.

[JustinKyleJames]

In many places imeta detects an error due to missing arguments but does not return immediately which leads to uncaught exceptions. The code should return with SYS_INVALID_INPUT in these cases.

Examples:

imeta ls -d
imeta ls -C
imeta mod -d
imeta mod -d file.dat
imeta rm -d
etc.

This is related to #18 but is meant to be more general to cover all of these cases.

[JustinKyleJames]

All tests passed so closing this issue.