From 5e8d0454d1aa5388a7045bdcb3069e41e4474957 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Mon, 2 Mar 2026 09:38:36 +0200
Subject: mapr client: replace runtime panics with errors

Task: 4e6d7744-3f5c-4880-9e5d-368ece96470d
---
 internal/clients/maprclient.go    | 35 ++++++++++++++++++++---------------
 internal/mapr/client/aggregate.go |  2 +-
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/internal/clients/maprclient.go b/internal/clients/maprclient.go
index cfbffee..2af038f 100644
--- a/internal/clients/maprclient.go
+++ b/internal/clients/maprclient.go
@@ -99,11 +99,13 @@ func (c *MaprClient) Start(ctx context.Context, statsCh <-chan string) (status i
 	go c.periodicReportResults(ctx)
 
 	status = c.baseClient.Start(ctx, statsCh)
-	
+
 	// Always write final result for cumulative mode (includes outfile case)
 	if c.cumulative {
 		dlog.Client.Debug("Writing final mapreduce result")
-		c.reportResults(true)
+		if err := c.reportResults(true); err != nil {
+			dlog.Client.Error("Unable to write final mapreduce result", err)
+		}
 		dlog.Client.Debug("Final result written")
 	}
 
@@ -149,22 +151,23 @@ func (c *MaprClient) periodicReportResults(ctx context.Context) {
 		select {
 		case <-time.After(c.query.Interval):
 			dlog.Client.Debug("Gathering interim mapreduce result")
-			c.reportResults(false)
+			if err := c.reportResults(false); err != nil {
+				dlog.Client.Error("Unable to gather mapreduce result", err)
+			}
 		case <-ctx.Done():
 			return
 		}
 	}
 }
 
-func (c *MaprClient) reportResults(finalResult bool) {
+func (c *MaprClient) reportResults(finalResult bool) error {
 	if c.query.HasOutfile() {
-		c.writeResultsToOutfile(finalResult)
-		return
+		return c.writeResultsToOutfile(finalResult)
 	}
-	c.printResults()
+	return c.printResults()
 }
 
-func (c *MaprClient) printResults() {
+func (c *MaprClient) printResults() error {
 	var result string
 	var err error
 	var numRows int
@@ -182,18 +185,18 @@ func (c *MaprClient) printResults() {
 		result, numRows, err = c.globalGroup.SwapOut().Result(c.query, rowsLimit)
 	}
 	if err != nil {
-		dlog.Client.FatalPanic(err)
+		return fmt.Errorf("unable to render mapreduce result: %w", err)
 	}
 
 	if result == c.lastResult {
 		dlog.Client.Debug("Result hasn't changed compared to last time...")
-		return
+		return nil
 	}
 	c.lastResult = result
 
 	if numRows == 0 {
 		dlog.Client.Debug("Empty result set this time...")
-		return
+		return nil
 	}
 
 	rawQuery := c.query.RawQuery
@@ -210,19 +213,21 @@ func (c *MaprClient) printResults() {
 			"to %d rows! Use 'limit' clause to override!", numRows, rowsLimit))
 	}
 	dlog.Client.Raw(fmt.Sprintf("%s\n", result))
+	return nil
 }
 
-func (c *MaprClient) writeResultsToOutfile(finalResult bool) {
+func (c *MaprClient) writeResultsToOutfile(finalResult bool) error {
 	dlog.Client.Debug("writeResultsToOutfile called", "finalResult", finalResult, "cumulative", c.cumulative)
 	if c.cumulative {
 		if err := c.globalGroup.WriteResult(c.query, finalResult); err != nil {
-			dlog.Client.FatalPanic(err)
+			return fmt.Errorf("unable to write cumulative mapreduce result: %w", err)
 		}
 		dlog.Client.Debug("WriteResult completed for cumulative mode")
-		return
+		return nil
 	}
 	if err := c.globalGroup.SwapOut().WriteResult(c.query, true); err != nil {
-		dlog.Client.FatalPanic(err)
+		return fmt.Errorf("unable to write non-cumulative mapreduce result: %w", err)
 	}
 	dlog.Client.Debug("WriteResult completed for non-cumulative mode")
+	return nil
 }
diff --git a/internal/mapr/client/aggregate.go b/internal/mapr/client/aggregate.go
index 2e9b61a..2750643 100644
--- a/internal/mapr/client/aggregate.go
+++ b/internal/mapr/client/aggregate.go
@@ -67,7 +67,7 @@ func (a *Aggregate) Aggregate(message string) error {
 	// Merge data from group into global group.
 	isMerged, err := a.globalGroup.MergeNoblock(a.query, a.group)
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("unable to merge aggregate data for server %s: %w", a.server, err)
 	}
 	if isMerged {
 		// Re-init local group (make it empty again).
-- 
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