EPUB exports cannot be opened in KOReader due to the "mimetype" file being missing from exported EPUBs

[AMaliciousSalad]

Steps to reproduce

1. Install Version 2.0 with/without a prior version installed
2. Add a novel via a source (tested with Ao3 and Scribblehub)
3. Download any/all chapters
4. Use the "Export Novel as EPUB" button/feature with any set of options enabled
5. Attempt to open exported EPUB with KOReader
6. KOReader displays error message: "Failed recognizing or parsing this file: unsupported or invalid document. KOReader will exit now."
7. KOReader exits upon next tap of the screen

Expected behavior

When attempting to open the exported EPUB it should just open normally with no error message or subsequent closing of the KOReader app.

Actual behavior

Upon trying to open the exported EPUB the error message "Failed recognizing or parsing this file: unsupported or invalid document. KOReader will exit now." Appears and KOReader closes on next screen input.

LNReader version

2.0.0

Android version

Android 13

Device

Boox Go Color 7 (Gen II)

Other details

During my testing I found that the "mimetype" file that epub readers use to verify that an epub is in fact an epub is missing from the root directory of EPUBs exported from version 2.0.0 when it wasn't in version 2.0.0_Beta3. Upon inserting that file into the root directory of an EPUB generated by LNReader v2.0.0 and attempting to then open the EPUB with KOReader the EPUB behaves correctly.

Acknowledgements

• [x] I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
• [x] I have written a short but informative title.
• [x] If this is an issue with a source, I should be opening an issue in the sources repository.
• [x] I have updated the app to version 2.0.0.
• [x] I will fill out all of the requested information in this form.