DB Manager: QGIS mouse hangs when previewed virtual layer is unavailable

[qgib]

Author Name: Harrissou Santanna (@DelazJ)
Original Redmine Issue: 16477
Affected QGIS version: master
Redmine category:db_manager

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Given that when you preview a virtual layer in DB Manager, that layer is removed from the Layers panel (see #24385), if you inadvertently click again on that layer in the DB Manager, QGIS hangs on and the mouse pointer becomes a busy one. You can still click on other layers (after some time) and use the mouse normally. However, the pointer remains in the busy status (which is disturbing) and does not take the look of any other tool you could select (Identifier, zoom, pan...).
The only solution is to close QGIS.

An error has occurred while executing Python code: 

AttributeError: 'NoneType' object has no attribute 'isValid' 
Traceback (most recent call last):
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 66, in runPrev
    return self._loadTablePreview(item)
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 115, in _loadTablePreview
    if not vl.isValid():
AttributeError: 'NoneType' object has no attribute 'isValid'


Python version: 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)] 
QGIS version: 2.99.0-Master Master, f1d4ac3 

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

• easy_fix was configured as 0
• regression was configured as 0

[qgib]

Author Name: Harrissou Santanna (@DelazJ)

---

This was a side-effect of #24385

---

• resolution was changed from to fixed/implemented
• status_id was changed from Open to Closed
• description was changed from Given that when you preview a virtual layer in DB Manager, that layer is removed from the Layers panel (see DB Manager: previewing layers in Virtual layers section remove them from the Layers panel #24385), if you inadvertently click again on that layer in the DB Manager, QGIS hangs on and the mouse pointer becomes a busy one. You can still click on other layers (after some time) and use the mouse normally. However, the pointer remains in the busy status (which is disturbing) and does not take the look of any other tool you could select (Identifier, zoom, pan...).
  The only solution is to close QGIS.

An error has occurred while executing Python code: 

AttributeError: 'NoneType' object has no attribute 'isValid' 
Traceback (most recent call last):
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 66, in runPrev
    return self._loadTablePreview(item)
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 115, in _loadTablePreview
    if not vl.isValid():
AttributeError: 'NoneType' object has no attribute 'isValid'


Python version: 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)] 
QGIS version: 2.99.0-Master Master, f1d4ac3 
   to Given that when you preview a virtual layer in DB Manager, that layer is removed from the Layers panel (see #24385), if you inadvertently click again on that layer in the DB Manager, QGIS hangs on and the mouse pointer becomes a busy one. You can still click on other layers (after some time) and use the mouse normally. However, the pointer remains in the busy status (which is disturbing) and does not take the look of any other tool you could select (Identifier, zoom, pan...).
The only solution is to close QGIS.

An error has occurred while executing Python code: 

AttributeError: 'NoneType' object has no attribute 'isValid' 
Traceback (most recent call last):
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 66, in runPrev
    return self._loadTablePreview(item)
  File "C:/OSGEO4~1/apps/qgis-dev/./python/plugins\\db_manager\\layer_preview.py", line 115, in _loadTablePreview
    if not vl.isValid():
AttributeError: 'NoneType' object has no attribute 'isValid'


Python version: 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)] 
QGIS version: 2.99.0-Master Master, f1d4ac3