Need better error handling when commands are not invoked in the expected way

[weitsang]

For instance,

vv write

cause the following:

thread 'main' panicked at '`write` needs to consume an input, but no named input is found, specify it using `+input=input_name`', src/pipeline/executor.rs:87:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The error message should guide the users in how to invoke the command correctly and ask users to run --help for details.

[YoHoSo]

Now, some of the panics are removed and replaced with an error message. For instance,

vv write

The output:

Error: `write` needs to consume an input, but no named input is found, specify it using `+input=input_name`
Use --help for more information