Bug 535162 - [content assist] Possible NPE during async computeFilteredProposals

Change-Id: Ib1ea59e69c54811982ee484676be8e77f982fda7
Signed-off-by: Dawid Pakuła <zulus@w3des.net>

org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/AsyncCompletionProposalPopup.java

diff --git a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/AsyncCompletionProposalPopup.java b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/AsyncCompletionProposalPopup.java
index 26f260d..4178c78 100644
--- a/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/AsyncCompletionProposalPopup.java
+++ b/org.eclipse.jface.text/src/org/eclipse/jface/text/contentassist/AsyncCompletionProposalPopup.java
@@ -304,7 +304,7 @@
 
 	@Override
 	protected List<ICompletionProposal> computeFilteredProposals(int offset, DocumentEvent event) {
-		if(fComputedProposals.size() > 0 && fComputedProposals.get(0) instanceof ComputingProposal) {
+		if(fComputedProposals != null && fComputedProposals.size() > 0 && fComputedProposals.get(0) instanceof ComputingProposal) {
 			Set<CompletableFuture<List<ICompletionProposal>>> remaining = Collections.synchronizedSet(new HashSet<>(fFutures));
 			for (CompletableFuture<List<ICompletionProposal>> future : fFutures) {
 				future.thenRun(() -> {