Contributing: fixed some typos

eng/build-utils.ps1

@@ -119,7 +119,7 @@ function Exec-CommandCore([string]$command, [string]$commandArgs, [switch]$useCo
     }
   }
   finally {
-    # If we didn't finish then an error occured or the user hit ctrl-c.  Either
+    # If we didn't finish then an error occurred or the user hit ctrl-c.  Either
     # way kill the process
     if (-not $finished) {
       $process.Kill()

src/EditorFeatures/Test/EditAndContinue/EditAndContinueWorkspaceServiceTests.cs

@@ -770,7 +770,7 @@ public async Task BreakMode_ErrorReadingPdbFile()
             var diagnostics = await service.GetDocumentDiagnosticsAsync(document2, CancellationToken.None).ConfigureAwait(false);
             Assert.Empty(diagnostics);
 
-            // an error occured so we need to call update to determine whether we have changes to apply or not:
+            // an error occurred so we need to call update to determine whether we have changes to apply or not:
             Assert.True(await service.HasChangesAsync(sourceFilePath: null, CancellationToken.None).ConfigureAwait(false));
 
             Assert.Empty(_emitDiagnosticsUpdated);
@@ -838,7 +838,7 @@ public async Task BreakMode_ErrorReadingSourceFile()
             var diagnostics = await service.GetDocumentDiagnosticsAsync(document2, CancellationToken.None).ConfigureAwait(false);
             Assert.Empty(diagnostics);
 
-            // an error occured so we need to call update to determine whether we have changes to apply or not:
+            // an error occurred so we need to call update to determine whether we have changes to apply or not:
             Assert.True(await service.HasChangesAsync(sourceFilePath: null, CancellationToken.None).ConfigureAwait(false));
 
             Assert.Empty(_emitDiagnosticsUpdated);

src/Features/Core/Portable/EditAndContinue/CommittedSolution.cs

@@ -282,7 +282,7 @@ public void CommitSolution(Solution solution)
         /// Returns true if the PDB contains a document record for given <paramref name="sourceFilePath"/>,
         /// in which case <paramref name="checksum"/> and <paramref name="algorithm"/> contain its checksum.
         /// False if the document is not found in the PDB.
-        /// Null if it can't be determined because the PDB is not available or an error occured while reading the PDB.
+        /// Null if it can't be determined because the PDB is not available or an error occurred while reading the PDB.
         /// </summary>
         private bool? TryReadSourceFileChecksumFromPdb(string sourceFilePath, ProjectId projectId, out ImmutableArray<byte> checksum, out SourceHashAlgorithm algorithm)
         {

src/Features/Core/Portable/EditAndContinue/EditAndContinueWorkspaceService.cs

@@ -507,7 +507,7 @@ public void DiscardSolutionUpdate()
                 }
 
                 // This method is only called when the EnC is about to apply changes, at which point all active statements and 
-                // their exception regions will be needed. Hence it's not neccessary to scope this query down to just the instruction
+                // their exception regions will be needed. Hence it's not necessary to scope this query down to just the instruction
                 // the debugger is interested at this point while not calculating the others.
 
                 var baseActiveStatements = await editSession.BaseActiveStatements.GetValueAsync(cancellationToken).ConfigureAwait(false);