Shape transform scale property breaks down upon changing it to zero or negative value.

Steps to reproduce:
1. Create a new project.
2. In hierarchy window, right-click > effects > particle system.
3. Go to Inspector and expand Shape property of Particle system component.
4. Click the 'Shape transform scale editing mode' button.
5. Drag the center scale handle in such a way that scale value should be set to zero or negative.

Actual result:
Shape transform scale property breaks down upon changing it to zero or negative value.

Expected result:
Shape transform scale property changes to zero.

Note:
1. Shape transform toolbar introduced in 2019.1.0a8.
2. Editor crashes on Windows platform in 2019.1.0a15 and 2019.2.0a2 by resetting Particle system properties.
3. The video is attached for reference.

Reproducible in:
2019.2.0a2, 2019.1.0b1, 2019.1.0a8

Environment:
Mac and windows
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Steps to reproduce the crash bug (Windows platform only):
1. Follow all the above steps.
2. Change the Shape transform rotation and position values.
3. Change the Particle System GO Scale and rotation values from the transform component.
4. Go to a Particle system component and reset via cogwheel.

========== OUTPUTTING STACK TRACE ==================
Stack Trace of Crashed Thread 15612:
0x00007FF762135B7E (Unity) PAL_Memory_Free
0x00007FF76364B3C8 (Unity) PAL_Timer_WaitForAtLeast
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF75F8E4BBF)
0x00007FF75F8E4BBF (Unity) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF75F91A9EA)
0x00007FF75F91A9EA (Unity) (function-name not available)
0x00007FF761BAB9AE (Unity) PAL_Memory_Free
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF76063D642)
0x00007FF76063D642 (Unity) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF76024B47F)
0x00007FF76024B47F (Unity) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF760600E57)
0x00007FF760600E57 (Unity) (function-name not available)
0x00007FF760B8658D (Unity) PAL_Memory_Free
0x00007FF760B957CD (Unity) PAL_Memory_Free
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF760758CEC)
0x00007FF760758CEC (Unity) (function-name not available)
0x00007FF760B8CB47 (Unity) PAL_Memory_Free
0x00007FF760B982AD (Unity) PAL_Memory_Free
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF7608D804D)
0x00007FF7608D804D (Unity) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FF7608D4E98)
0x00007FF7608D4E98 (Unity) (function-name not available)
0x00007FF760B94653 (Unity) PAL_Memory_Free
0x00007FF760B9E0E6 (Unity) PAL_Memory_Free
0x00007FF7636283D2 (Unity) PAL_Timer_WaitForAtLeast
0x00007FFAA8AB3034 (KERNEL32) BaseThreadInitThunk
0x00007FFAA9253691 (ntdll) RtlUserThreadStart