[Bug] single bar with encode config cannot trigger axis tooltip

[Justin-ZS]

Version

5.6.0

Link to Minimal Reproduction

demo

Steps to Reproduce

see the demo.

Current Behavior

hover over the bar, no tooltip gets shown

Expected Behavior

show tooltip

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

Fallbacking to data config and adding a dummty data: [ '' ] can fix.
But that workaround will cause all related logics have to handle two cases.

[likexin-kk]

I think this is not a bug
For the example you provided, which has only one dimension mapped to the y-axis, you can set it to
Tooltip. axisPointer. axis='y 'to achieve the desired effect

https://echarts.apache.org/examples/zh/editor.html?c=bar-simple&code=PYBwLglsB2AEC8sDeAoWsAeBBDEDOAXMmurGAJ4gCmRA5AMYCGYVA5sAE7m0A0J6AegGwAJs0ZEA2rVoBdEgF8-6cjnxFUpMpRqxaAN0YAbAK5Vai5WWDAjkEBv6w8AC2AB3ImA5mr6bxCsrFQcdIy4eLxO4fgACsAQ0CyhxFroMYR63E4KliR4IRBUmZJOmmlCouJSAMwADLJ-pFTQ9MAiukiw5FINsEpO_jp0AEaMHFFpsEaMI1RGjlPorh5ePlSD_TlWjSRiYIwFYFJlm3jAJhz0uqVLsJL18lNPpLnouwoA3EA