com.intellij.util.IncorrectOperationException: SingleRootFileViewProvider

Starting with IDEA 2018, I have severe problems with my file contents going out of sync with IDEA's internal model. We already had a similar issue here. What happens is that basically all the time I get a 

File text mismatch: tree.length=5; psi.length=4; this=FILE; vp=SingleRootFileViewProvider{myVirtualFile=LightVirtualFile: /test.m, content=com.intellij.psi.AbstractFileViewProvider$PsiFileContent@7f777c9b}

I have created a detailed issue report on YouTrack, but maybe others ran into the same exception and know how to debug this. The two exceptions I see have the same underlying cause that the text of the ViewProvider is out of sync with the tree. Can anyone help me?

SingleRootFileViewProvider{myVirtualFile=LightVirtualFile: /test.m, content=com.intellij.psi.AbstractFileViewProvider$PsiFileContent@7f777c9b} 
com.intellij.util.IncorrectOperationException: SingleRootFileViewProvider{myVirtualFile=LightVirtualFile: /test.m, content=com.intellij.psi.AbstractFileViewProvider$PsiFileContent@7f777c9b}
 at com.intellij.psi.impl.BlockSupportImpl.makeFullParse(BlockSupportImpl.java:239)
 at com.intellij.psi.impl.BlockSupportImpl.reparse(BlockSupportImpl.java:101)
 at com.intellij.psi.impl.BlockSupportImpl.reparseRange(BlockSupportImpl.java:68)
 at com.intellij.codeInsight.completion.OffsetsInFile.reparseFile(OffsetsInFile.kt:66)
 at com.intellij.codeInsight.completion.OffsetsInFile.replaceInCopy(OffsetsInFile.kt:56)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.insertDummyIdentifier(CodeCompletionHandlerBase.java:481)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.prepareCompletionParameters(CodeCompletionHandlerBase.java:327)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lambda$null$2(CodeCompletionHandlerBase.java:291)
 at com.intellij.openapi.application.impl.ApplicationImpl.tryRunReadAction(ApplicationImpl.java:1134)
 at com.intellij.codeInsight.completion.AsyncCompletion.tryReadOrCancel(CompletionThreading.java:181)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lambda$doComplete$3(CodeCompletionHandlerBase.java:290)
 at com.intellij.codeInsight.completion.AsyncCompletion.lambda$null$0(CompletionThreading.java:108)
 at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$1(CoreProgressManager.java:157)
 at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:580)
 at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:525)
 at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:85)
 at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:144)
 at com.intellij.codeInsight.completion.AsyncCompletion.lambda$startThread$1(CompletionThreading.java:104)
 at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:305)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
 at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
 at java.util.concurrent.FutureTask.run(FutureTask.java)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at java.lang.Thread.run(Thread.java:745)

Second Exception

File text mismatch: tree.length=5; psi.length=4; this=FILE; vp=SingleRootFileViewProvider{myVirtualFile=LightVirtualFile: /test.m, content=com.intellij.psi.AbstractFileViewProvider$PsiFileContent@7f777c9b} 
java.lang.AssertionError: File text mismatch: tree.length=5; psi.length=4; this=FILE; vp=SingleRootFileViewProvider{myVirtualFile=LightVirtualFile: /test.m, content=com.intellij.psi.AbstractFileViewProvider$PsiFileContent@7f777c9b}
 at com.intellij.psi.impl.source.PsiFileImpl.getText(PsiFileImpl.java:341)
 at com.intellij.codeInsight.completion.CompletionAssertions.createFileTextAttachment(CompletionAssertions.java:110)
 at com.intellij.codeInsight.completion.CompletionAssertions.assertCompletionPositionPsiConsistent(CompletionAssertions.java:152)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.findCompletionPositionLeaf(CodeCompletionHandlerBase.java:354)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.createCompletionParameters(CodeCompletionHandlerBase.java:345)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.prepareCompletionParameters(CodeCompletionHandlerBase.java:336)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lambda$null$2(CodeCompletionHandlerBase.java:291)
 at com.intellij.openapi.application.impl.ApplicationImpl.tryRunReadAction(ApplicationImpl.java:1134)
 at com.intellij.codeInsight.completion.AsyncCompletion.tryReadOrCancel(CompletionThreading.java:181)
 at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lambda$doComplete$3(CodeCompletionHandlerBase.java:290)
 at com.intellij.codeInsight.completion.AsyncCompletion.lambda$null$0(CompletionThreading.java:108)
 at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$1(CoreProgressManager.java:157)
 at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:580)
 at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:525)
 at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:85)
 at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:144)
 at com.intellij.codeInsight.completion.AsyncCompletion.lambda$startThread$1(CompletionThreading.java:104)
 at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:305)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
 at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
 at java.util.concurrent.FutureTask.run(FutureTask.java)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 at java.lang.Thread.run(Thread.java:745)