Not allowed using tab between INSTRUCTION and arguments

[lucasvc]

Dockerfile's accept to separate with tab's or n-spaces the INSTRUCTION from the arguments. Best practices doesn't indicate what is the prefered way.
Eclipse shows different errors. In example:

FROM    ubuntu:14.04

Shows the error:

required (...)+ loop did not match anything at input 'FROM'

But when instead of a tab, there are two or more spaces, the error changes to:

mismatched input ' ubuntu:14.04\r\n' expecting RULE_ID

In RUN instruction, the error is:

mismatched input '' expecting RULE_ONE_SPACE_AND_WHATEVER

[lucasvc]

Neither is allowed tab between arguments. In example:

ENV SUPER_VAR   /usr/local/variable

Shows error the error:

no viable alternative at input 'SUPER_VAR'

[l0rd]

Thank you @lucasvc for your feedback. I'll add tab support in the next days.