Multi template fails to render graphs

[sukhwinder33445]

It is not possible to create graphs with multi3 template graphs if different metrics or different numbers of metrics are given per graph.

Current Behavior:

Steps to Reproduce:

1. Select a Service which uses multi(3) template for graphs.
2. Extend multi3-service.metrics_filters to include warn metric filter in multi.ini template file as following:

[multi3-service.metrics_filters]
value = "$service_name_template$.perfdata.$multi1$.$multi2$.$multi3$.value"
warn = "$service_name_template$.perfdata.$multi1$.$multi2$.$multi3$.warn"

3. Add following prefdata through the quick-action proccess check result:

'a1::b1::c1'=3894494000B;5797273500;6119344250;0;6441415000
'a2::b2::c2'=0;5797273500;6119344250;0;6441415000
'a3::b3::c3'=3894494000B;;6119344250;0;6441415000

Result:
Example (with 3 graphs):
graph 1: value, min, max, crit, warning
graph 2: value, min, max, crit, warning
graph 3: value

As the graph 3 has only 1 metric AND warn is missing in it, it will throw an error.