As a mismatch reviewer
I want to be notified of errors in my list of Item IDs I provide
in order to submit a valid list of IDs
**Problem:**
We need to handle cases where someone enters something in the Item ID input field that is not an Item ID. Cases that we should think about:
* syntactical errors (the user gets the same error message below the input field for all of these):
** some lines are valid IDs but others are not
** several IDs on one line instead of one per line
* the input field is empty -> we show a warning below the input field
**Screenshots/mockups:**
**Syntactic validation of input (error):**
{F34619521}
Link to [[ https://www.figma.com/file/sgK1Go5my7ShZ1HQIxV2FI/Mismatch-Finder?node-id=1119%3A22625 | Figma ]] for error message
Copy: //One or more Item identifiers couldn't be processed. Please make sure to add only one identifier per line, without spaces or commas.
Item identifiers should only be a set of valid numbers preceded by the letter Q (for example: Q1256).//
__________
**Empty submission attempt (warning):**
{F34619534}
Link to [[https://www.figma.com/file/sgK1Go5my7ShZ1HQIxV2FI/Mismatch-Finder?node-id=1119%3A22625 | Figma ]] for warning message
Copy: //Please provide the Item identifiers in order to perform the check.//
__________
**BDD**
GIVEN an Item ID input field
AND the user inputs syntactically incorrect IDs
WHEN clicking submit
THEN an error is shown below the Item ID input field informing the user that the input has syntax issues
GIVEN an Item ID input field
AND the user leaves it empty
WHEN clicking submit
THEN a warning is shown below the Item ID input field informing the user that they need to input an Item ID
**Acceptance criteria:**
[ ] Input is syntactically validated on submit
[ ] We consider a line as syntactically incorrect if it is not "Q+natural numbers"
[ ] We only accept one ID per line, not several IDs per line
[ ] Warning is shown when submitting an empty list of Item IDs
**Notes:**
* We only do syntactical checking. We do not check for example if an Item exists for a given Item ID.
* The validation should happen when the button is clicked, but before the form is sent.