Does Not Detect Tab has Been Erased - Incorrect Popup

[ErikaGrandy]

Issue Title: Does Not Detect That Tablature Has Been Erased - Incorrect Popup

Version: 0.3.0

Platform: Windows 10

Steps to Reproduce:

Please note that this bug does not always occur. The popup is sometimes the other popup detecting an empty text area, but every so often this error occurs instead.

1. Using "Load from File" button, upload a txt file containing a tablature
2. Press "Convert"
3. Go back to input tab
4. Remove tablature from text window
5. Press "Convert" again

At this step, the bug occurs when the popup below shows up:

In some occasions the other popup (Index 0 out of bounds) is displayed. I have found that repeating the steps above will always eventually lead to the "at line 3 column 1" error.

Expected: A user friendly popup message indicating that conversion cannot be completed as the text area is empty. The message should contain no unfamiliar words, and should not specify a specific location for the error as their is no text. As there is not specific error in the tablature, no red highlighting should occur.

Actual: An error message that states "Input Parsing Error at line 3 column 1". Once this popup is exited and any change is made to the text area, the entire text area is highlighted red. If a new tab is pasted in, the entire tab remains highlighted red.

Priority: Low/Medium - This bug is low priority as it is rare. It is likely a simple fix once the other empty text area bug is fixed, and it just seems like something is triggering the popup to have an error at specifically line 3 column 1. If this bug begins to be more common it would become medium priority, as it continuously affects user experience.

Severity: Medium - While this bug is rare, once it occurs it continues to affect the users experience. Even a properly pasted in tablature is completely highlighted red, and is confusing to the user why the whole tab is being declared as having an issue.

Upload a txt file containing a tablature

Delete tablature from text area

Attempt to Convert

Entire Text Area is Highlighted