In communication, an origin/source/sender/encoder (who) encodes a message/content (what) into a signal/form (how) and a destination/sink/receiver/decoder (to whom) decodes the signal/form (how) into a message/content (what).

To properly answer the question, one should distinguish between *encoding errors*, *signal defects*, *decoding failures*, *decoding errors* and *message defects* (the terms ‘error’, ‘defect’ and ‘failure’ are defined in [software testing](https://softwaretestingfundamentals.com/error-defect-failure/)). An error in a process (encoding or decoding) may result in a defect in its product (encoded signal or decoded message), and a defect in a product (encoded signal) may result in a failure in a subsequent process (decoding).

An encoding error at the lexical level or grammatical level may result in
- a signal defect at the lexical level (e.g. ‘This iz the end.’), in which case the destination can detect the encoding error, can classify the encoding error as lexical and can correct the signal defect to the nearest valid signal (e.g. ‘This is the end.’); or
- a signal defect at the grammar level (e.g. ‘Your the best.’), in which case the destination can detect the encoding error, cannot classify the encoding error and can correct the signal defect to the nearest valid signal (e.g. ‘You’re the best.’, which happens to be a [heterograph](https://en.wikipedia.org/wiki/Homophone) of the defective signal); or
- no signal defect (e.g. ‘Give me an egg sample.’), in which case the destination cannot detect the encoding error, cannot classify the encoding error and cannot correct the signal defect.

Thus, unless the destination knows the origin’s message, the destination can only detect lexical encoding errors resulting in lexical signal defects. However the destination can always detect lexical and grammatical signal defects.

Coming back to the examples given in the question: ‘Your the best.’ and ‘I likes music.’ have an encoding error (of unknown level) resulting in a grammatical signal defect, while ‘She preatend to be asleep.’ and ‘This iz the end.’ have a lexical encoding error resulting in a lexical signal defect.