Backend: handle null response from Eth server #3929

Job	Run time
linux-github--dotnet-and-mono	4m 5s
linux-github--dotnet-and-mono	4m 5s
linux-vanilla--stockdotnet6-and-newmono	5m 49s
linux-vanilla--stockdotnet6-and-newmono	5m 49s
linux-vanilla--newmono-only	8m 14s
linux-vanilla--newmono-only	8m 14s
linux-github--dotnet-and-newmono	6m 54s
linux-github--dotnet-and-newmono	6m 54s
linux-vanilla--stockdotnet6-and-stockmono	6m 37s
linux-vanilla--stockdotnet6-and-stockmono	6m 37s
linux-vanilla--stockdotnet6-only	5m 6s
linux-vanilla--stockdotnet6-only	5m 6s
linux-vanilla--stockmono-only	1m 29s
linux-vanilla--stockmono-only	6m 25s
macOS--dotnet6-and-mono	13m 4s
macOS--dotnet6-and-mono	13m 4s
macOS--dotnet6-only	4m 17s
macOS--dotnet6-only	4m 17s
macOS--mono-only	11m 0s
macOS--mono-only	11m 0s
windows--dotnet6-and-legacyFramework	5m 58s
windows--dotnet6-and-legacyFramework	5m 58s
windows--dotnet6-only	6m 1s
windows--dotnet6-only	6m 1s
windows--legacyFramework-only	11m 22s
windows--legacyFramework-only	11m 22s
conventions	0s
conventions	2m 25s
snap_pkg	0s
snap_pkg	0s
snap_pkg_beta	0s
snap_pkg_beta	0s
	3h 7m 13s

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