I've been consistently getting a crash in (I think) the rendering engine on MacOS.  This has been present through multiple releases (1.15.x, and maybe as early as 1.14.x).  It happens with either a second or a main display, and happens with both the "beta launcher" as well as the non-beta launcher.

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Process: java [49446]
Path: /Users/USER/Library/Application Support/minecraft/*/jre.bundle/Contents/Home/bin/java
Identifier: java
Version: 1.0 (1.0)
Code Type: X86-64 (Native)
Parent Process: launcher [49431]
Responsible: launcher [49431]
User ID: 501

Date/Time: 2020-06-28 11:22:51.395 -0700
OS Version: Mac OS X 10.15.4 (19E287)
Report Version: 12
Anonymous UUID: 7393370B-5B6A-833F-2D76-1ED8D2CAD943

Sleep/Wake UUID: 25337E50-D18D-4E6A-A06C-FEC1D2086BAE

Time Awake Since Boot: 560000 seconds
Time Since Wake: 120 seconds

System Integrity Protection: enabled

Crashed Thread: 0 Java: Render thread Dispatch queue: com.apple.main-thread

Exception Type: EXC_BAD_ACCESS (SIGABRT)
Exception Codes: KERN_INVALID_ADDRESS at 0x000000000000000c
Exception Note: EXC_CORPSE_NOTIFY

VM Regions Near 0xc:
-->
__TEXT 000000010ee94000-000000010eea6000 [ 72K] r-x/rwx SM=COW /Users/USER/Library/Application Support/minecraft/*/jre.bundle/Contents/Home/bin/java

Application Specific Information:
abort() called
java(49446,0x11311cdc0) malloc: *** error for object 0x7ffc6d063f20: pointer being freed was not allocated

Thread 0 Crashed:: Java: Render thread Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x00007fff6f7b733a __pthread_kill + 10
1 libsystem_pthread.dylib 0x00007fff6f873e60 pthread_kill + 430
2 libsystem_c.dylib 0x00007fff6f73e808 abort + 120
3 libsystem_malloc.dylib 0x00007fff6f83450b malloc_vreport + 548
4 libsystem_malloc.dylib 0x00007fff6f83740f malloc_report + 151
5 libglfw.dylib 0x000000012ed99fec 0x12ed91000 + 36844
6 libglfw.dylib 0x000000012ed99ed5 0x12ed91000 + 36565
7 libglfw.dylib 0x000000012ed9e73a 0x12ed91000 + 55098
8 com.apple.CoreFoundation 0x00007fff3571e9cf _CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER_ + 12
9 com.apple.CoreFoundation 0x00007fff3571e963 ___CFXRegistrationPost1_block_invoke + 63
10 com.apple.CoreFoundation 0x00007fff3571e8d8 _CFXRegistrationPost1 + 372
11 com.apple.CoreFoundation 0x00007fff3571e544 ___CFXNotificationPost_block_invoke + 80
12 com.apple.CoreFoundation 0x00007fff356ee6bd -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1554
13 com.apple.CoreFoundation 0x00007fff356edb69 _CFXNotificationPost + 1351
14 com.apple.Foundation 0x00007fff37d64866 -[NSNotificationCenter postNotificationName:object:userInfo:] + 59
15 com.apple.AppKit 0x00007fff33497e97 _NSApplicationPerformScreenInvalidationReactions + 826
16 com.apple.AppKit 0x00007fff33498b55 ___NSMainRunLoopPerformBlockInModes_block_invoke + 25
17 com.apple.CoreFoundation 0x00007fff35728bac _CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK_ + 12
18 com.apple.CoreFoundation 0x00007fff35728af4 __CFRunLoopDoBlocks + 379
19 com.apple.CoreFoundation 0x00007fff357279eb __CFRunLoopRun + 912
20 com.apple.CoreFoundation 0x00007fff35726ffe CFRunLoopRunSpecific + 462
21 com.apple.HIToolbox 0x00007fff3435aabd RunCurrentEventLoopInMode + 292
22 com.apple.HIToolbox 0x00007fff3435a6f4 ReceiveNextEventCommon + 359
23 com.apple.HIToolbox 0x00007fff3435a579 _BlockUntilNextEventMatchingListInModeWithFilter + 64
24 com.apple.AppKit 0x00007fff329a5c99 _DPSNextEvent + 883
25 com.apple.AppKit 0x00007fff329a44e0 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1352
26 libglfw.dylib 0x000000012eda33c3 0x12ed91000 + 74691
27 ??? 0x000000011316c9d4 0 + 4615227860
28 ??? 0x000000011315ec4d 0 + 4615171149
29 ??? 0x000000011315ec4d 0 + 4615171149
30 ??? 0x000000011315ec4d 0 + 4615171149
31 ??? 0x000000011315ec4d 0 + 4615171149
32 ??? 0x000000011315ec4d 0 + 4615171149
33 ??? 0x000000011315ec4d 0 + 4615171149
34 ??? 0x000000011315ec4d 0 + 4615171149
35 ??? 0x000000011315ec4d 0 + 4615171149
36 ??? 0x00000001131577a7 0 + 4615141287
37 libjvm.dylib 0x00000001102ea39e JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710
38 libjvm.dylib 0x0000000110321110 jni_invoke_static(JNIEnv_, JavaValue, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) + 447
39 libjvm.dylib 0x0000000110319e8a jni_CallStaticVoidMethod + 349
40 java 0x000000010ee9793e JavaMain + 2481
41 java 0x000000010ee9959c -[JavaLaunchHelper launchJava:] + 42
42 com.apple.Foundation 0x00007fff37df61bd __NSThreadPerformPerform + 204
43 com.apple.CoreFoundation 0x00007fff35728f12 _CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION_ + 17
44 com.apple.CoreFoundation 0x00007fff35728eb1 __CFRunLoopDoSource0 + 103
45 com.apple.CoreFoundation 0x00007fff35728ccb __CFRunLoopDoSources0 + 209
46 com.apple.CoreFoundation 0x00007fff357279fa __CFRunLoopRun + 927
47 com.apple.CoreFoundation 0x00007fff35726ffe CFRunLoopRunSpecific + 462
48 java 0x000000010ee9a463 CreateExecutionEnvironment + 871
49 java 0x000000010ee961ac JLI_Launch + 1952
50 java 0x000000010ee9c4c0 main + 101
51 java 0x000000010ee95a04 start + 52

}}

The full crash report is attached.